Fix PatchTree performance issues (#755)

When building the tree, I've implemented a few improvements:

- We no longer traverse the full ancestry for every leaf node- we exit
early when we find a node that already exists
- We no longer search the entire tree to see if a node id exists before
creating one with that id, we just check if is in the map

CHANGELOG.md

@@ -22,6 +22,7 @@
 * Added better support for `Font` properties ([#731])
 * Add new plugin template to the `init` command ([#738])
 * Added rich Source diffs in patch visualizer ([#748])
+* Fix PatchTree performance issues ([#755])
 
 [#745]: https://github.com/rojo-rbx/rojo/pull/745
 [#668]: https://github.com/rojo-rbx/rojo/pull/668
@@ -44,6 +45,7 @@
 [#731]: https://github.com/rojo-rbx/rojo/pull/731
 [#738]: https://github.com/rojo-rbx/rojo/pull/738
 [#748]: https://github.com/rojo-rbx/rojo/pull/748
+[#755]: https://github.com/rojo-rbx/rojo/pull/755
 
 ## [7.3.0] - April 22, 2023
 * Added `$attributes` to project format. ([#574])